Method and apparatus for dampening rudder vibration

ABSTRACT

An apparatus is provided for dampening rudder vibration of a motorboat. The apparatus may include a tiller assembly rotatable about a pivot point adjacent the stern of the motorboat, the tiller assembly including a tiller arm extending in a first direction from the pivot point and configured to be rotated about the pivot point by a user, and/or a damper mounted on the tiller assembly extending in a second direction from the pivot point. The damper may be configured to rotate integrally with the tiller arm, and the damper may include a mass that is sufficient to dampen vibrations of the tiller. A method of using the apparatus for dampening rudder vibration is also disclosed.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/102,354 filed Oct. 2, 2008, and entitled METHOD AND APPARATUS FORDAMPENING RUDDER VIBRATION, the entire contents of which areincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates, in general, to an apparatus for dampening ruddervibration and methods for its use.

2. Description of Related Art

A typical motorboat is steered with a steering wheel operably connectedto a rudder via a cable and tiller arm, or other suitable means. Forexample, rotational movement of the steering wheel causes linear motionthrough the cable, which in turn moves a tiller arm and the rudder. Asthe cable moves back-and-forth, it effects a back-and-forth orside-to-side pivoting motion on the tiller arm in a well known manner soas to pivot the rudder as desired and effect steering of the boat.

In certain instances, however, tension and compression within the cableand/or other factors may contribute to vibration of the rudder. Forexample, a boat may be prone to rudder vibration or chatter when theboat is traveling at a certain speed, or when the boat is being loadedonto a trailer. Such vibration or chatter may cause less than optimalsteering control, undesired vibration propagating through the cable tothe steering wheel, unwanted noise, and other undesired effects.

It would therefore be useful to provide suitable means which overcomethe above and other disadvantages of known motorboat steeringassemblies.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is directed to an apparatus fordampening rudder vibration of a motorboat. The apparatus may include atiller assembly rotatable about a pivot point adjacent the stern of themotorboat, the tiller assembly including a tiller arm extending in afirst direction from the pivot point and configured to be rotated aboutthe pivot point by a user, and/or a damper mounted on the tillerassembly extending in a second direction from the pivot point. Thedamper may be configured to rotate integrally with the tiller arm, andthe damper may include a mass that is sufficient to dampen vibrations ofthe tiller.

The first direction and the second direction may be at least about 90°apart. The first direction and the second direction may be substantiallyopposite one another. A center of mass of the damper may be disposed ata distance from the pivot point, wherein the distance may be less thanabout 50% of a length of the tiller arm. The damper may include anelongated member including a first and a second end, wherein the firstend may be disposed at the pivot point, and wherein the second endincluding a width that may be larger than a width of the first end. Thedamper may include an elongated member including a first and a secondend, wherein the first end may be disposed at the pivot point, andwherein the second end including a thickness that may be larger than athickness of the first end. The damper may include an elongated memberhaving a first and a second end. The first end may be disposed at thepivot point, and the second end may include a density that may be largerthan a density of the first end.

The damper may include an elongated member having a first and a secondend. The first end may be disposed at the pivot point, and the dampermay further include a mass member at the second end. The mass member mayinclude a width that may be larger than a width of the first end. Themass member may include a thickness that may be larger than a thicknessof the first end. The mass member may include a density that may belarger than a density of the first end. A center of mass of the massmember may be disposed substantially in the second direction from thepivot point. A center of mass of the mass member may be displaced fromthe second direction.

The damper may include an elongated member including a first and asecond end, wherein the first end may be disposed at the pivot point,and wherein the second end may be curved. The second end may be curvedsubstantially in a circular arc. An end of the mass member may becurved. The end of the mass member may be curved substantially in acircular arc.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description of the Invention, which togetherserve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of an motorboat for which an exemplaryapparatus for dampening rudder vibration may be used in accordance withvarious aspects of the present invention.

FIG. 2A is an enlarged perspective view of an exemplary rudder andtiller arm that may be used on the motorboat of FIG. 1.

FIG. 2B is a plan view of an exemplary tiller arm and cable assemblythat may be used on the motorboat of FIG. 1.

FIG. 3A is an enlarged perspective view of the rudder and tiller arm ofFIG. 2A incorporating an exemplary apparatus for dampening ruddervibration in accordance with the present invention.

FIG. 3B is an exploded perspective view of the rudder and tiller arm ofFIG. 3A.

FIGS. 4A-C are plan views of the tiller and cable of FIG. 2Bincorporating the an exemplary apparatus of FIG. 3A, each figureillustrating the rudder and tiller arm in left-turn, straight-ahead, andright-turn modes of operation.

FIG. 5 is a perspective view of an exemplary apparatus for dampeningrudder vibration may be used on the motorboat of FIG. 1 in accordancewith various aspects of the present invention.

FIGS. 6A and 6B are plan views of other exemplary apparatuses fordampening rudder vibration may be used on the motorboat of FIG. 1 inaccordance with various aspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Turning now to the drawings, wherein like components are designated bylike reference numerals throughout the various figures, attention isdirected to FIG. 1 which illustrates a motorboat 30 having an otherwiseconventional steering assembly 32 including a steering wheel 33 operablyconnected to a rudder 35 via a steering cable 37 and a tiller assembly39 having a tiller arm 40. As the steering wheel is rotated left andright, rotational motion is applied to the cable by otherwiseconventional means to case linear motion of an inner cable 42 relativeto a cable housing 44. As the inner cable moves back-and-forth, tensileand compressive is applied by the cable on the tiller arm to effectpivoting motion of the rudder. For example, rotating the steering wheelto the left causes the inner cable to move forward in the mannerillustrated by arrow F to cause tiller arm and rudder to rotatecounterclockwise in the manner illustrated by arrow CCW to effect aleftward turn, as shown in FIG. 4B. Similarly, rotating the steeringwheel to the right will effect a rightward turn, as shown in FIG. 4C,and returning the steering wheel to its neutral position will effectstraightforward travel, as shown in FIG. 4A.

In accordance with the present invention, a dampening unit 46 Theinvention generally provides with a damper 47 attached to tiller arm 40.The damper can be of any construction useful in damping vibrations ofthe rudder 35. Exemplary embodiments of the damper are described below.

A tiller assembly 39 is rotatable about a pivot point 49 to steermotorboat 30. The tiller assembly includes tiller arm 40 extending inone direction, and damper 47 extending in another. The term “tiller arm”is used herein to mean the operable portion of the tiller assembly, i.e.the portion that is rotated by a user to rotate rudder 35 and steer themotorboat. In some embodiments, the tiller arm is rotated by steeringwheel 33 via a cable 37, but other methods of rotation, such as directmanipulation by a user, are also within the scope of the invention. Onewill appreciate that the tiller assembly may have other suitableconfigurations in accordance with the present invention. For example, atiller yoke and or other suitable means may be provided to translate thelinear motion of the steering cable to rotating motion of the rudder.

The damper 47, as mentioned above, makes up the part of the tillerassembly 39 that extends in a direction other than the direction of thetiller arm 40. This may be any direction that is deemed appropriate by aperson of ordinary skill in the art, based on the specific designrequirements of the boat for which the tiller assembly is being used.The direction of the damper should preferably be spaced significantlyapart from the direction of the tiller arm, such as by at least about90°. In the illustrated embodiments, the two directions aresubstantially opposite one another.

The damper 47 moves integrally with the tiller arm 40 and rudder 35. Tothis end, it may be cast or otherwise formed as a single piece with thetiller arm, as illustrated in FIG. 5. Alternatively, it may be madeseparately and attached to the tiller arm, such as with a bolt 51 andbolt holes 53, as illustrated in FIGS. 3A and 3B.

Generally, the damper 47 has a mass that is sufficient to dampvibrations and chatter of the rudder 35 and tiller arm 40. One willappreciate that the actual mass may vary with the dimensions and shapeof the rudder, the dimensions and configuration of the tiller assembly,and other assorted design criteria. Any tiller that has a significantamount of mass located in a direction other than the direction of thetiller arm may serve to dampen vibration and chatter in accordance withvarious aspects of the present invention.

To achieve optimal results, the center of mass of the damper 47 shouldbe spaced some distance apart from the pivot point 49. This may beaccomplished in various ways. In the illustrated embodiments, the damper47 is made up of an elongated member or rod 56, and mass member 54attached to the end of the rod. Depending, of course, on the dimensionsand densities of the rod and mass member, the center of mass of theillustrated embodiments can sometimes be approximated as the center ofmass of the mass member. It is preferable that the center of mass of thedamper 47 is displaced from the pivot point 49 by a distance that is atpreferably less the length of the tiller arm 40, and, in the illustratedembodiments, this distance is approximately equal to the length of thetiller arm.

One will appreciate, however, that the mass and distance of the massmember may vary in order to provide a suitable moment arm. For example,depending upon design constraints, in some instances it may bebeneficial to locate a very heavy mass member very close to the pivotpoint, while in other cases it may be advantageous to locate arelatively light mass member relatively far form the pivot point.

While the illustrated embodiments of the damper 47 include a mass member54 that is both wider and thicker than the rod 56, other embodiments arewithin the scope of the appended claims. For example and withoutlimitation, the damper may not include a separate mass member, but mayinstead be a single elongated member having a tapered shape that growswider, thicker, or both towards its distal end. Some embodiments mayinclude a mass member of a different, denser material than that of therod 56. In these embodiments, the mass member may or may not be widerand/or thicker than the rod 56. Still other embodiments may include asmall, dense mass member embedded within the material of the rod 56. Anyconfiguration that provides a mass of sufficient size, and a center ofmass at a sufficient distance from the pivot point, is within the scopeof the invention.

Turning now to FIGS. 6A and 6B, in some embodiments, one end 58 of themass member 54 is curved, such as in the circular arc shown. Thisconfiguration may be useful in boats where space is particularlylimited. When the motorboat is being steered, the tiller assembly 39rotates around the pivot point 49 such that the end 58 of the massmember traces a circular arc. Therefore, the illustrated shape helpsensure that there is ample space for a mass member of sufficient size.

As shown in FIG. 6A, the mass member 54 may be placed centrally on therod 56, i.e. such that its center of mass is along the axial directionof the rod (assuming uniform density in the mass member of FIG. 6A). Ifthere are additional spatial restraints, however, this does notnecessarily have to be the case. As shown in FIG. 6B, the mass membermay be placed somewhere other than centrally on the rod, i.e. such thatits center of mass is displaced from the axial direction of the rod(again, assuming uniform density). One will appreciate that the specificangle between the rod and the direction of center of mass of the dampermay have little or no effect on damping characteristics.

The amount of mass and its distance from the pivot point 49, on theother hand, are important variables in achieving desired dampingcharacteristics, and can, of course, be selected by a person of ordinaryskill in the art for the particular boat in which they are being usedthrough routine experimentation.

For convenience in explanation and accurate definition in the appendedclaims, the terms “left” or “right”, “counterclockwise” or “clockwise”,“forward” and “rearward”, and other relative terms are used to describefeatures of the exemplary embodiments with reference to the positions ofsuch features as displayed in the figures and are not intended to belimiting, absolute terms.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

1. An apparatus for dampening rudder vibration of a motorboat, theapparatus comprising: a tiller assembly rotatable about a pivot pointadjacent the stern of the motorboat, the tiller assembly including atiller arm extending in a first direction from the pivot point andconfigured to be rotated about the pivot point by a user; and a dampermounted on the tiller assembly extending in a second direction from thepivot point, wherein the damper is configured to rotate integrally withthe tiller arm, and wherein the damper includes a mass that issufficient to dampen vibrations of the tiller.
 2. The apparatus of claim1, wherein the first direction and the second direction are at leastabout 90° apart.
 3. The apparatus of claim 2, wherein the firstdirection and the second direction are substantially opposite oneanother.
 4. The apparatus of claim 1, wherein a center of mass of thedamper is disposed at a distance from the pivot point, wherein thedistance is less than about 50% of a length of the tiller arm.
 5. Theapparatus of claim 1, wherein the damper comprises an elongated memberincluding a first and a second end, wherein the first end is disposed atthe pivot point, and wherein the second end including a width that islarger than a width of the first end.
 6. The apparatus of claim 1,wherein the damper comprises an elongated member including a first and asecond end, wherein the first end is disposed at the pivot point, andwherein the second end including a thickness that is larger than athickness of the first end.
 7. The apparatus of claim 1, wherein thedamper comprises an elongated member including a first and a second end,wherein the first end is disposed at the pivot point, and wherein thesecond end including a density that is larger than a density of thefirst end.
 8. The apparatus of claim 1, wherein the damper comprises anelongated member including a first and a second end, wherein the firstend is disposed at the pivot point, and wherein the damper furtherincluding a mass member at the second end.
 9. The apparatus of claim 8,wherein the mass member comprises a width that is larger than a width ofthe first end.
 10. The apparatus of claim 8, wherein the mass membercomprises a thickness that is larger than a thickness of the first end.11. The apparatus of claim 8, wherein the mass member comprises adensity that is larger than a density of the first end.
 12. Theapparatus of claim 8, wherein a center of mass of the mass member isdisposed substantially in the second direction from the pivot point. 13.The apparatus of claim 8, wherein a center of mass of the mass member isdisplaced from the second direction.
 14. The apparatus of claim 1,wherein the damper comprises an elongated member including a first and asecond end, wherein the first end is disposed at the pivot point, andwherein the second end is curved.
 15. The apparatus of claim 14, whereinthe second end is curved substantially in a circular arc.
 16. Theapparatus of claim 8, wherein an end of the mass member is curved. 17.The apparatus of claim 16, wherein the end of the mass member is curvedsubstantially in a circular arc.